Two-cycle engine



April 9, 1940. R. DAUB TWO CYCLE ENGINE Filed Aug. 25, 1938 Wm w Im A m Patented Apr. 9, 1940 UNITED SATES 2,196,252 TWO-CYCLE ENGINE Rudolph Daub, Paterson,

N. J., assignor to Wright Aeronautical Corporation, a corporation of New York Application August 25,

11 Claims.

This invention relates to two-cycle internal combustion engines, and is particularly concerned with improvements to provide for better scavenging and better combustion than may be obtained with conventional structures.

The provisions of the invention are adapted for use with compression-ignition engines or with those adapted to utilize electric ignition, a particular object of the invention being to provide 0 structure which defines a definite path of gas flow in an engine cylinder during engine operation. A further object is to provide an arrangement whereby a greatly improved shape of combustion chamber is accomplished. Further chjects comprise the provision of structural devices by which improved engine performance may result, in connection with which reference may be made to the detailed description below, and the drawing, in which:

at Fig. 1 is a longitudinal section through an engine cylinder showing the piston thereof in the bottom dead center position;

Fig. 2 is a longitudinal section showing the piston on its top dead center position;

at; Fig.3 is a section on the line t3 of Fig. 1, and

Fig. 4 is a section on the line il-il of Fig. 1.

An engine cylinder in is provided with jackets l l for the circulation of a cooling fluid and, toward the lower end of its effective volume is provided so with a plurality of intake ports l2 defined by bridge elements it, the several intake ports lying on one side of a diameter of the cylinder. site the intake ports, exhaust ports it are formed, these being defined by cored bridge pieces I5 35 through the cores of which coolant fluid may flow. A cylinder head it is suitably attached to the top of the cylinder, the head being domed as at IT to provide a combustion chamber, the head in addition having a coolant jacket l8 and a central fuel an injection nozzle iii. The injection nozzle l9 may be replaced by a spark plug if the engine be of the electric ignition type. From the cylinder head l6 depends a substantially flat but hollow plate 20, the hollow thereof being indicated at 2 i, this plate is being integral with the head and being joined thereto at the upper edges of the plate as at 22,

the hollow 2! of the plate communicating freely with the jacket id of the cylinder head. Between the plate edge junctions 22 an opening 24 is de- 50 fined which lies directly beneath the fuel injection nozzle Iii, this hollow, in efiect,forming a part of the combustion space H.

a A piston 26 is reciprocable in the cylinder and is provided with a central slot or well 28 of flattened 55 form within which the plate is adapted to nest Oppo- 1938, Serial No. 226,627

when the piston is elevated above its bottom center position. The well 28 is defined by walls 30 integral with the piston, these walls, with the side walls of the piston forming bosses for a pair of piston pins 32 upon which the ends 36% of a forked 5 connecting rod are journaled. The use of the forked connecting rod and two piston pins allows of the placement of the piston pins above the bottom of the well 28, thereby reducing the overall length of the piston. The bottom of said well 28 w is defined by a wall 3? so that the piston is sealed against the escape of gases by means of the effective piston head 39, the walls 30 and the well bottom 3i. It is contemplated that there shall be a fairly loose fit between the sides of the plate as it and the side walls of the slot 28, there being no metal-to-metal contact between these surfaces.

In the operation of the system, intake air enters the ports l2 and must pass upwardly, through the opening 241 and downwardly on the opposite side of the plate 20 before it may leave through the exhaust ports i l. Thereby, during engine operation, the exhaust gases remaining in the cylinder must be completely scavenged by the incoming air after which the piston rises, sealing off the ports l2 and id and compressing the air charge in the cylinder proper. At the top of the piston stroke fuel is injected through the jet is into the combustion space ill, ignition of the fuel charge driving the piston downwardly until the ports l2--lii are uncovered. As is conventional in two-cycle engines, the exhaust ports are opened slightly before the intake ports on the down stroke of the piston, exhaust gas thereupon leaving through the ports l4 and shortly thereafter incoming air 2% washes the exhaust gases thoroughly from within the cylinder. In conventional engines, a baflle rises from the piston head close to the intake ports whereby the incoming air is directed upwardly with the object of accomplishing fairly to complete scavenging of exhaust gas from the cylinder. However, such baffles are only partly effective and in high speed engines there is a considerable amount of exhaust gas remaining in the cylinder after each cycle of operation which tends to 4.5 reduce the power. With the arrangement of this invention, complete scavenging of exhaust gas is virtually assured and additionally, great turbulence of the fresh air charge is afforded upon the upstroke of the piston in the interest of more efilcient combustion. The turbulent compressed gaseswhich are confined to the combustion space l1 will readily effect an admixture of fuel with air when the fuel is admitted, and by the shape of the combustion chamber afforded by the provisions of the invention, rapid and complete combustion of the fuel charge is assured. It will be noted that the combustion chamber, when the piston is in its uppermost position, is greatly confined and is of more or less spherical shape whereby the distance from the fuel jet to the most remote part of the combustion chamber is small. There are no long channels or separated chambers which would have the tendency of slowing th ombustion process and promoting detonation.

It is realized, of course, that the plate 29 is in the hottest part of the cylinder, and accordingly the plate is hollow, as previously described, by which it may be liquid cooled. To assure a favorable and positive path for the cooling liquid, a bafiie 12, shown in Fig. 3, extends from the top of the plate part way toward the bottom thereof and within the plate hollow so that, if cooling fluid be admitted to the head it through an opening t3, such fluid will follow the path indicated by the curved arrow to leave the plate and head through an exit opening Ml. This extra cooling area made available by the plate 20 consists in keeping the center of the piston cool due to heat flow from the piston head down the walls 39 and to the plate. Since the surface area of a piston increases as the square of the bore, and since the volume thereof increases as the cube of the bore, the provision of this extra cooling plate is particularly favorable in large bore engines as it provides extra cooling surface which would not otherwise be available. Thus, the provisions of the invention point to the possibility of increasing the bore and power of engines beyond their present range.

While I have described my invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding my invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. I aim in the appended claims to cover all such modifications and changes.

I claim as my invention:

1. In an internal combustion engine, in combination, a cylinderhaving a head, a baiile plate depending from the head having a through opening at the top, the width of said baffle being less than the cylinder bore, and a piston reciprocable in said cylinder having a slot therein within which said baflle slides when the piston is above bottom center, said bailie lying without said piston when the latter is at bottom center thereby dividing the cylinder into two compartments in v communication with one another through said baflle opening and through the clearance space at the sides of said baffle.

2. In an internal combustion engine, in combination, a cylinder having a head, a baffle plate i depending from the head having a through opening at the top, the width of said bafile being less than the cylinder bore, a piston reciprocable in said cylinder having a slot therein within which said bailie slides when the piston is above bottom center, said baflie lying without said piston when the latter is at bottom center thereby dividing the cylinder into two compartments in communication with one another through said battle opening and through the clearance space at the sides of said baiile, said baflle having a hollow therein for cooling liquid, and inlet and outlet ducts in communication with said hollow.

3. In an internal combustion engine, in combination, a cylinder, a head therefor having a flat ybiiiile extendin downwardly therefrom dividing greases the cylinder into adjacent compartments of substantially semi-cylindrical shape, said bailie having an opening through the top part thereof establishing communication between said compartments.

i. In an internal combustion engine, in combination, a cylinder, a head therefor having a flat baiiie extending downwardly therefrom dividing the cylinder into adjacent compartments of substantially semi-cylindrical shape, said baffle having an opening through the top part thereof establishing communication between said compartments, and a piston in the cylinder having a slot of such depth as to receive some part of the baffle throughout the full stroke of the piston.

5. In an internal combustion engine, in combination, a cylinder, at head therefor having a fiat baiiie extending downwardly therefrom dividing the cylinder into adjacent compartments-of substantially semi-cylindrical shape, said bafiie having an opening through the top part thereof establishing communication between said compartments, a piston in the cylinder having a slot of such depth as to receive some part of the baffle throughout the full stroke of the piston, and means for cooling said bailie.

6. In an internal combustion engine, in combination, a cylinder, a head therefor having a fiat baiiie extending downwardly therefrom dividing the cylinder into adjacent compartments of substantially semi-cylindrical shape, said bafiie having an opening through the top part thereof establishing communication between said compartments, and a piston in the cylinder having a slot of such depth as to receive some part of the baiiie throughout the full stroke of the piston, said cylinder head being domed adjacent said bafiie opening to define a combustion space.

7 In an internal combustion engine, in combination, a cylinder, a head therefor having a flat baflle extending downwardly therefrom dividing the cylinder into adjacent compartments of substantially semi-cylindrical shape, said baiile having an opening through the top part thereof establishing communication between said compartments, and a piston in the cylinder having a slot of such depth as to receive some part of the baffle throughout the full stroke of the piston, said cylinder having inlet and exhaust ports therein respectively on opposite sides of said baflle, whereby fluid entering said inlet port must travel through the baiiie opening prior to exit through the exhaust port.

8. In a two-cycle engine comprising a ported cylinder member and a piston member reciprocable therein to cover and uncover said ports, a fiat bailie carried by one said member and separating certain of said ports from direct communication, said baflle having a through opening remote from said ports, said other member having a slot into which the baiiie is slidable upon reciprocation of the piston in the cylinder.

9. In a two-cycle engine comprising a cylinder member having ports and a piston member reciprocable therein to cover and uncover said ports, a flat bailie carried by one said member and separating certain of said ports from direct communication, said bailie having a through opening remote from said ports, said other member having a slot into which the baiiie is slidable upon reciprocation of the piston in the cylinder, coolant Jackets embracing said cylinder, and means for introzllucing coolant to said bailie during engine opera- 10. An engine including a cylindrical piston having a flat axial slot extending across and downwardly from the piston head the walls of the slot and piston defining segmental hollows therebetween, a bifurcated connecting rod having portions extending into said hollows, and knuckle pins connecting each rod portion to respective slot and piston walls.

11. An engine including a cylindrical piston having an axial slot extending downwardly from the piston head, a bifurcated connecting rod having portions between the piston and slot walls, knuckle pins connecting each said rod portion to respective slot and piston walls, and a cylinder having a substantially flat plate depending therefrom adapted to enter the piston slot upon relative reciprocation of the piston in the cylinder.

RUDOLPHVDAUB. 

